So sorry about your little hen, along with all the others you have had put down over the years. It is never easy to say good bye to our beloved friends. But you gave them a good life, and that is the most important thing. And did the right thing in the end.
Sounds like she may have suffered a head injury. She may or may not survive. I have had a few cases of quail with neurological issues and have found that high doses of vitamin/mineral/amino acids/omega's/probitiotics, etc... have done wonders for cases involving the brain.